Hydrogen production has become a priority in many refinery operations, especially when trying to produce lower sulfur gasoline and diesel fuels. Along with increased hydrogen consumption for deeper hydrotreating, additional hydrogen is typically needed for processing heavier and higher sulfur crude slates. New safe and reliable sources of hydrogen for refineries and clean fuels are now required to meet the needs of the future transportation fuel market and the drive towards higher refinery profitability.
One method of hydrogen production is electrochemical reforming, also known as anode depolarized electrolysis, using a constant cell voltage. Hydrogen production by electrochemical reforming is conceptually simple: two electrical leads are inserted into a mixture of a depolarizing agent and water, an electric potential is applied between the leads, and two different chemical reactions take place, one at each electrode. At the cathode, water is electrochemically-reduced to form hydrogen gas. At the anode, the depolarizing agent is electrochemically oxidized. By utilizing small voltages, electrochemical reforming avoids the production, of oxygen gas, an inherent product in conventional water electrolysis. Because hydrogen is produced in the absence of oxygen, there is a reduced explosion hazard associated with membraneless operation, relieving the need for gas-separating technology.
One common problem with standard electrochemical reforming is electrode deactivation. Regardless of the various reaction parameters, that can be optimized such as temperature, pH, voltage, or the electrochemical reforming medium, the rate of the overall electrochemical reforming process deteriorates rapidly following the initiation of the process. Over a matter of minutes the deactivation of the electrodes will significantly diminish the reaction kinetics, and for some depolarizing agents the reaction will die completely.